Hydrogen cyanide gas is an important toxin in smoke from industrial and residential fires, industrial accidents and release through acts of terrorism. Cyanide acts extremely rapidly and can cause death within minutes. In the United States, there are approximately 5,000-10,000 deaths due to smoke inhalation annually. Cyanide may be responsible for many of these deaths, because it is released from the combustion of plastics, wool, and other nitrogen-containing materials.
Combustion of synthetic products that contain carbon and nitrogen, such as plastics and synthetic fibers, releases cyanide. There have been numerous studies of fire victims to assess the lethal levels of cyanide. Fire survivors have been found to have <20 μM cyanide in blood, while victims were found to have levels greater than 20-30 μM and in some cases as much as 100 μM cyanide in blood (Baud et al., 1991, N. Engl. J. Med., 325: 1761-1766). Cigarette smoke also contains cyanide. The nonsmoker typically averages about 0.06 μg/mL (2.31 μM) of cyanide in blood, whereas a smoker typically averages 0.17 μg/mL (6.5 μM) (Clark et al., 1981, Lancet: 1332-1335).
Cyanide is also readily used in industry in the making of plastics, in the recovery of gold and silver from ores, and in the electroplating of metals, such as silver, gold, platinum and copper (Baskin and Brewer, In Medical Aspects of Chemical and Biological Warfare, Eds. Sidell, Takafuji and Franz, TMM publications, Washington, 1997, Chapter 10, pages 271-286). Cassava root, which is used to make tapioca and is a major food source in tropical regions, releases cyanide when improperly prepared, and chronic cyanide exposure leads to konzo or tropical ataxic neuropathy. The drug sodium nitroprusside, a nitric oxide releasing agent used to treat patients with acute hypertension, releases five cyanide ions for every nitric oxide molecule and is limited by cyanide toxicity. Due to its toxicity when inhaled or ingested, cyanide could also be used as a terrorist weapon.
Therefore, there exists a need to frequently and efficiently monitor cyanide amount in the environment and in the human body to evaluate cyanide exposure and its associated risks. In cases of cyanide poisoning or suspected cyanide poisoning, there exists a need to rapidly measure cyanide amount for treatment decisions.
A variety of methods exist for measuring cyanide levels. These include a variety of chemical approaches and expensive techniques, including spectrophotometry, fluorometry, high performance liquid chromatography (HPLC), mass spectrometry, HPLC-mass spectrometry, and gas chromatography. Spectrophotometric assays can analyze multiple samples relatively quickly, but lack sensitivity and specificity, while gas chromatography, mass spectrometry, and HPLC require expensive equipment and allow only limited sample throughput. Several existing methods require laborious multistep sample pre-treatment are not amenable for use in the field. Neither does there exist an integrated device which processes the sample, induces and controls the chemical reactions and provides an objective measure of cyanide within the sample. Thus, a field-deployable device for rapid cyanide detection is clearly needed.